Limestone type tennis court



United States Patent 9 LIMESTONE TYPE TENNIS COURT Donald D. Klotz, Iowa City, Iowa Application January 9, 1956, Serial Nb. 557,943

1 Claim. (Cl. 94-7) My invention relates to tennis courts, and one of the important objects contemplated is the provision of a new a Another object of this invention is to provide an improved tennis court having an automatic watering system.

- A still further object of my invention is to provide in a tennis court an improved playing surface that requires little, if any rolling once it has been initially rolled and packed into proper condition.

A further object inhering in this invention is to provide a tennis court of the above class with a quick drying playing surface that after a rain may be used as soon as tennis courts having concrete or asphalt surfaces, or the like.

Other objects and'advantages of this invention reside in the details of construction and correlation of the various parts and will be apparent as the description proceeds.

This invention consists of novel parts and combination of parts to be hereinafter described whereby the objects set forth are attained, as pointed out in the claims, and illustrated in the accompanying drawing, in which: Fig. l is a top plan view of a tennis court showing the regulation court markings, broken lines to locate the subsurface water pipes, and a cutaway section to more clearly illustrate one of such pipes, and,

Fig. 2 is an enlarged cross sectional view of the layer formation of this tennis court taken on the line 22 of Fig. 1.

Referring to the drawings Fig. 1 illustrates a top plan view of a tennis court showing the regulation markings such as the respective base lines and 12, the respective service lines 14 and 16, the alleys, 18 and 20, and the net 22. The kind of playing surface generally used for tennis courts are of several types such as grass, clay, concrete, and asphalt, for example, each of which has both advantages and disadvantages. Concrete and asphalt surfaces are of course much less resilient than grass or clay but the markings can be painted on, the surfaces do not scuff easily and they are usable relatively quickly after a rain for obvious reasons. Grass and clay on' the other hand provide a surface which is less tiring to play on but also requires considerable work in maintenance and upkeep and, compared to concrete and asphalt, are unusable after rains ,for a relatively long period.

My new tennis court, shown in cross section in Fig. 2 was developed after extensive experimentation to provide an improved playing surface substantially combining most of the advantages of the types of courts referred to above without containing their respective disadvantages. In building this tennis court I have used a clay base or foundation 24 because of its known lack of ability to readily absorb water, for reasons which will become apparent as this description proceeds. On this clay base I have built up, one upon the other, four subsurface layers Patented June 10, 1958 ICC of granular particles of limestone 26, 28, 30 and 32 respectively (Fig. 2) and topped it with the surface layer or playing surface 34 which is also composed of granular limestone particles. The formation and depth of each respective layer is important in producing the desired results on the playing surface 34 and thus the several layers are preferably constructed as follows:

Base 24 will, of course, be leveled and layer 26 which is-first placed on the base 24 consists of what is known as concrete stone, being individual stones approximately one fourth to three quarters of an inch in size and arranged as shown into a layer having a depth of three quarters inch to one inch. In this bottom layer 26 I have set a plurality of spaced apart parallel water pipes 36 to run longitudinally of the tennis court as shown in Fig. l

a and in these pipes at regular intervals preferably of one foot, I have provided water outlet openings 38 of approximately one thirty-second of an inch diameter. Pipes 36 are connected at one end of the tennis court by the cross pipe 40 which in turn is connected to a source of water supply controlled by valve 42. A valve 44 utilizes a moisture measuring block 46 which I place just below the playing surface 34 in some central place on one side of the net 22 as shown in Fig. 1 so that it opens and closes the water supply 42 in response to the moisture content of the playing surface. Valve 44 and block 46 are shown only in block diagrams since they are available commercially and no invention is claimed in the same per se. Individual valves 48 connecting each pipe 36 to pipe 40 may also be provided and it will be understood that these may be manually operable and maybe located on the surface in' some convenient place away from the playing area. Likewise, valve 42 may be manually operated, if desired.

With the bottom layer 26 and water pipe system in place, the next layer 28 which has a depth of one half to five eighths inch consists of granular particle ranging in size from two sixteenths to six sixteenths inch and known as chip stone or cover aggregate. Onto this is placed layer 30 containing coarse ag (agricultural) lime particles to provide a thickness of three quarters inch to one inch. These particles are the coarser parts of ag lime that will not pass through a No. 10 screen. Layer 30 is then covered by layer 32 which is seven eighths inch to one inch of ag lime capable of passing a No. 8 screen and this is covered by the top or playing surface 34 which has a depth of five eighths inch to three quarters inch and consists of ag lime that will pass through a No. 10 or 12 screen.

Each layer 26, 28, 3t), and 32 is lightly rolled as it is put in place and the top layer or playing surface 34 is subjected to heavier rolling and will require approximately one month to become adequately packed so that thereafter rolling becomes unnecessary.

It is pointed out that each layer as described is the result of screening the limestone from the quarry so that the size of the stones or particles is progressively smaller from the bottom layer 26 to the top layer 34. Note in Fig. 2 that the bottom three layers 26, 28 and 39 contain only individual stones, chips and particles respectively, whereas layer 3% is a combination of dust or powder with some limestone particles and the playing surface 34 is practically all powder so as to be susceptible of suitable packing. Slight variation in total layer depths are per- 3 in the bottom layer 26 and then rises by capillary action through the several layers to the surface. The moisture sensitive block 46 will be afiected by water reaching the top layer 34 so as to close valve 42 and thus the entire court is automatically kept supplied at all times with the proper amount of moisture.

It is deemed important that the relative depths of the several layers making up this tennis court be constructed substantially as described in order to assure the proper distribution of water as described. The base 24 is preferably of clay as previously mentioned since it wiil not readily absorb water coming from pipes 36 and thus gives the Water opportunity to rise through the several layers by capillary action. Any water absorbing substance used in place of the clay 24 would in effect drain the water away so that there would be no watering of the upper layers at all. 1

The arrangement of the several layers as to depth and size of aggregate used was determined after extensive tests to best provide a suitable playing surface that could be watered by subsurface watering as described. Larger stones in the bottom layer 26, for example, provided too coarse a strata for water to rise by capillary action and layers of either greater or lesser depth than those described were found to be undesirable since the proper distribution of water was not obtained.

It is also pointed out that while I preferably use limestone material in all layers of this court structure, cinder material may be used in the bottom two layers 26 and 28 so long as the cinders used are of comparable size to the concrete stone and chips above described. However, cinders will break down in time and a court made by using them will not last as long as one using all limestone.

The watering system described here is shown as being within the limits of the playing area of the court but this is illustrative only and it will be understood that the pipes 36 can extend into the back playing court or to the backstops without changing the principle of operation.

I should also like to make clear that while I describe a complete court including a top layer or playing surface, the sub structures of this court without the top layer make an excellent foundation for receiving various commercially available surfacing materials for tennis courts.

It is submitted that the invention shown and described .4 is aptly suited to achieve the purposes intended and is characterized by a combination of highly useful and mu tually cooperating elements that combine their respective and proportionate functions in accomplishing the objects sought to be obtained.

It will be understood that the phraseology employed herein is for the purpose of description and not for limitation and that modifications and changes in the construction and arrangement of this invention can be made within the scope of what is claimed, without departing from the spirit and purpose thereof. Itis thus intended to cover by the claim, any modified forms of structure or mechanical equiivalents which may reasonably be included Within its scope.

I claim:

A tennis court structure, comprising five layers of granular particles of limestone one upon another, each of said layers being progressively less coarse from bottom to top and respectively comprising one fourth to three quarter inch concrete stones forming a layer depth of three quarters to one inch, two sixteenths to six sixteenths inch chip stones forming a layer depth of one half to live eighths inch, coarse agricultural lime particles incapable of passing through a No. 10 screen to form a layer depth three quarters to oneinch, agricultural lime particles capable of passing through a No. 8 screen to form a layer depth of seven eighths toone inch, agricultural lime particles capable of passing through a No. 10 or 12 screen to form a layer depth of live eighths to three quarter inch, and a water distributing system in said lowermost layer.

References Cited in the file of this patent UNITED STATES PATENTS 188,645 Lee Mar. 20, 1877 358,288 Moore Feb. 22, 1887 1,958,850 Foster May 15, 1934 2,067,356 Swinhoe Ian. 12, 1937 2,445,717 Richards July 20, 1948 FOREIGN PATENTS 3,221 Great Britain Aug. 24, 1877 321,244 Great Britain Nov. 7, 1929 392,026 Great Britain May 11, 1933 

